Hybrids

[hardyvermont]

This is the first year this F2 Pomelo x Poncirus has fruited.  It is grafted 5 ft up on a Poncirus which has not been pruned back.  It has gone through several winters without protection, including a low of about 6 F, -14.4 C.  Fruit does not appear to be ripe.  Brix is 8.5.  Taste is sour with Poncirus overtones.  Somewhat like a grapefruit picked too early.  Fruit is oval 5.5 inches (14 cm) at the widest and 4 (10 cm) inches high. 

[kumin]

Congratulations, what a large fruit! How early in the year did it flower? What is the ancestry of the tree?

[hardyvermont]

Congratulations, what a large fruit! How early in the year did it flower? What is the ancestry
estry of the tree?

The flowers were not noticed, when the fruit appeared it was a surprise.  It probably bloomed in early April.  The female parent is Hirado Buntan, the male is from a seed collected at the Arnold Arboretum. 

[tedburn]

Nice fruit and quite hardy plant, did you cross it and raise it from seed ? How long dit it take to fruit ?

[hardyvermont]

Nice fruit and quite hardy plant, did you cross it and raise it from seed ? How long dit it take to fruit ?

Yes, I made the original cross.  This is from a seedling from that cross.  It is about 8 years old.  It would have bloomed earlier if it had been planted in the ground sooner rather than kept in a pot. 

[Walt]

Congratulations.  Will you be planting the seeds?  If so, good luck and keep us up to date please.  If not, there are people who would like to grow them. 
I'm surprised it is winter hardy that far north.  That's very encouraging.  Walt

[hardyvermont]

Congratulations.  Will you be planting the seeds?  If so, good luck and keep us up to date please.  If not, there are people who would like to grow them. 
I'm surprised it is winter hardy that far north.  That's very encouraging.  Walt

I'm not keeping the seed.  You can have them.

[Ilya11]

This is the first year this F2 Pomelo x Poncirus has fruited.

Is it F1 or F2?

[Citradia]

That’s wonderful! Looks like you made your own citrumelo. Looks kind of like Dunstan. Congratulations.

[hardyvermont]

This is the first year this F2 Pomelo x Poncirus has fruited.

Is it F1 or F2?

F2

[hardyvermont]

That’s wonderful! Looks like you made your own citrumelo. Looks kind of like Dunstan. Congratulations.

Thanks.   There are differences.  The leaves are unifoliate, there are no thorns and the fruit is larger.  Dunstan may taste better, and has a nicer color.  There are more fruit on the tree and hopefully they will ripen enough before cold weather for a more positive evaluation.

[Ilya11]

Is it F2 seedling of your own F1 PomeloXPT cross?

[hardyvermont]

Is it F2 seedling of your own F1 PomeloXPT cross?

Yes, an F2 of the original cross.  The original crosses were made many years ago.  I moved and almost all of the plants were lost.  A few fruit were scavenged when I went back to my old place.  7 plants from one fruit have survived which appear to be zygotic.  Three have fruit now. 

[SoCal2warm]

From research I've looked into in the past, there's probably a higher than 50 percent chance the seedling you grew was nucellar, so it may be an exact clone of the original parent hybrid. But there's also a fair chance, maybe somewhere between 20 to 40 percent, that the seedling could have been zygotic (probably resulting from hermaphroditic sexual reproduction. If that's the case there is a chance the genes might get scrambled around to improve characteristics of edibility and cold hardiness. But even those chances of an improvement are probably 1 out of 4, or 1 out of 8 (I would guess, from apply basic statistics to how dominant/recessive gene pairs work). I know this is very speculative but maybe that will give you some small idea of what could be happening here and the chances of any change from what you did here.

I do find it very interesting that you chose to use an actual pomelo in your (original) cross.

[hardyvermont]

From research I've looked into in the past, there's probably a higher than 50 percent chance the seedling you grew was nucellar, so it may be an exact clone of the original parent hybrid. But there's also a fair chance, maybe somewhere between 20 to 40 percent, that the seedling could have been zygotic (probably resulting from hermaphroditic sexual reproduction. If that's the case there is a chance the genes might get scrambled around to improve characteristics of edibility and cold hardiness. But even those chances of an improvement are probably 1 out of 4, or 1 out of 8 (I would guess, from apply basic statistics to how dominant/recessive gene pairs work). I know this is very speculative but maybe that will give you some small idea of what could be happening here and the chances of any change from what you did here.

I do find it very interesting that you chose to use an actual pomelo in your (original) cross.

No, it is zygotic.  The parent had a smaller fruit.  The siblings have different characteristics

[SoCal2warm]

You might want to grow multiple seeds from the hybrid. I would expect if you grow enough of them, at least one of them should result in elimination of the unsavory poncirus taste. That is assuming that the genes behave as normal dominant/recessive pairs. I believe how gene expression works in citrus is a little more complicated.

Let B represent bad taste, and b represent lack of bad taste.
Also let C represent cold hardiness and c represent lack of cold hardiness. B is dominant over b which is recessive.

the first cross was the poncirus with the pure pomelo
BB CC x bb cc = Bb Cc

next you obtained a zygotic seed from the resulting previous hybrid
Bb Cc x Bb Cc =

these are the statistical probabilities:
BB CC
BB Cc
BB cC
BB cc
Bb CC
Bb Cc
Bb cC
Bb cc
bB CC
bB Cc
bB cC
bB cc
bb CC
bb Cc
bb cC
bb cc

only the last 4 possibilities will not have the bad poncirus taste. 4 out of 12 is a 1 in 4 probability. Out of that 1 in 4, 1 in 4 will not really have any cold hardiness. Half will have moderate cold hardiness, like the hybrid parent, and the remaining 1 out of 4 will have superior cold hardiness, better than the parent. That means there will be a 1 out of 16 chance the offspring (assuming they are all zygotic) will both lack a bad taste and also be more cold hardy than the first generation hybrid.
This is probably oversimplified, of course.

what you have now would probably be more like a Bb CC type.

I apologize for hijacking your thread if theory is not what you wanted the discussion to focus on.

[orangedays]

The fruit looks great.  This is a cross I am interested in.  Hirado Buntan is supposed to be 'quite cold hardy' and ripens in the fall with zygotic seedlings.  What I didn't realize was how big the fruit is until I saw the pictures Laaz posted. Does it ripen in the same year it flowers in? That seems extraordinary, given its size.  The size of this F2 fruit is really impressive and encouraging.  I  bought a Hirado Buntan this spring hoping maybe to make this cross next spring. But this is better.

If all the seed not already claimed, may I have some?

 I am also making a few crosses with PT to get away from the current nucellar hybrids and use these to back crosses to cold hardy citrus. After that, use the back crosses to hybridize to each other and to select for for good taste and hardiness. It might work for zone 8 as there are some sweet citrus that can almost survive 8a.

[hardyvermont]

The fruit looks great.  This is a cross I am interested in.  Hirado Buntan is supposed to be 'quite cold hardy' and ripens in the fall with zygotic seedlings.  What I didn't realize was how big the fruit is until I saw the pictures Laaz posted. Does it ripen in the same year it flowers in? That seems extraordinary, given its size.  The size of this F2 fruit is really impressive and encouraging.  I  bought a Hirado Buntan this spring hoping maybe to make this cross next spring. But this is better.

If all the seed not already claimed, may I have some?

 I am also making a few crosses with PT to get away from the current nucellar hybrids and use these to back crosses to cold hardy citrus. After that, use the back crosses to hybridize to each other and to select for for good taste and hardiness. It might work for zone 8 as there are some sweet citrus that can almost survive 8a.

There are 5 fruit altogether so there is more seed to come.  Waiting for further ripening to improve flavor and brix.  Plant probably blossomed in April.  The winters are too cold here to have fruit survive the winter. 
Good luck with your breeding, there are a few sweet citrus that can usually survive zone 8a winters, throwing in some poncirus background could get hardiness down another 5 degrees F. 

[orangedays]

These are pictures of 20 seed from the F2 PT X Hirado Buntan hardyvermont sent.  I pealed the seed to speed up germination. This also gives some ability to determine if the seed are poly-embryonic. 

These seed are larger then most, plump and 100% mono-embryonic.  So hopefully/probably zygotic. They are also very white which may will be useful in detecting future crossed to green seeded citrus.  I will plant them in the ground this spring when they are of size.

[Perplexed]

Deleted. you're germinating them indoors ?

[orangedays]

I am germinating them indoors.  After they come up ( in about two weeks - if seed coats removed ), I either place them in a south facing window or under grow lights. This way, I get a head start on the growing season and these may grow a few feet before next winter.

[poncirsguy]

Head start is everything when starting from seed.

[Perplexed]

Sprout now. Going to take them outside probably next month.

[vnomonee]

How did these grow for you?

Sprout now. Going to take them outside probably next month.

[1rainman]

You might want to grow multiple seeds from the hybrid. I would expect if you grow enough of them, at least one of them should result in elimination of the unsavory poncirus taste. That is assuming that the genes behave as normal dominant/recessive pairs. I believe how gene expression works in citrus is a little more complicated.

Let B represent bad taste, and b represent lack of bad taste.
Also let C represent cold hardiness and c represent lack of cold hardiness. B is dominant over b which is recessive.

the first cross was the poncirus with the pure pomelo
BB CC x bb cc = Bb Cc

next you obtained a zygotic seed from the resulting previous hybrid
Bb Cc x Bb Cc =

these are the statistical probabilities:
BB CC
BB Cc
BB cC
BB cc
Bb CC
Bb Cc
Bb cC
Bb cc
bB CC
bB Cc
bB cC
bB cc
bb CC
bb Cc
bb cC
bb cc

only the last 4 possibilities will not have the bad poncirus taste. 4 out of 12 is a 1 in 4 probability. Out of that 1 in 4, 1 in 4 will not really have any cold hardiness. Half will have moderate cold hardiness, like the hybrid parent, and the remaining 1 out of 4 will have superior cold hardiness, better than the parent. That means there will be a 1 out of 16 chance the offspring (assuming they are all zygotic) will both lack a bad taste and also be more cold hardy than the first generation hybrid.
This is probably oversimplified, of course.

what you have now would probably be more like a Bb CC type.

I apologize for hijacking your thread if theory is not what you wanted the discussion to focus on.

Probably similar to grapes. You just get less native flavors each time it's crossed with non native. It takes many generations to breed out those flavors. The number of hybrids with significant native ancestry like 30-50% but without native flavors are only a handful even after many generations of selective breeding and those are used over and over again in further breeding. But I like native flavors but they are bred out for wine.